很多新手对于GMAT数学不是十分自信,究其原因往往就是是由于对于GMAT数学知识点没有复习,而直接做题,为此小编特收集整理了关于统计的GMAT数学知识点,分享给大家,希望对大家有所帮助,文中观点仅供参考。
1. arithmetic mean : 算术平均值
2. median: 中位数
①The median is the middle value of a list when the numbers are in order.
②先排序,后取中。比如说一个数列{1,2,4,5,3},求它的中间数时,应该先排序变成{1,2,3,4,
5},然后取中为 3。如果数列含有偶数个数,取中间两个数,然后取这两个数的算术平均。
3. mode: 众数
① The mode of a list of numbers is the number that occurs most frequently in the list.
② A list of numbers may have more than one mode.
4. expectation: 期望
在 GMAT 数学中,期望就是算术平均值。
5. deviation 偏差
di=ai-E
6. variance 方差
1n2
D =
n i =1
7. standard deviation 标准差
s= D
例:Ⅰ.72,73,74,75,76
Ⅱ.74,74,74,74,74
Ⅲ.62,74,74,74,89
The data sets Ⅰ,Ⅱ,and Ⅲ above are ordered from greatest standard deviation to least standard deviation in
which of the following ?
Ⅰ,Ⅱ, Ⅲ Ⅰ, Ⅲ,Ⅱ Ⅱ, Ⅲ, Ⅰ Ⅲ, Ⅰ,Ⅱ Ⅲ,Ⅱ, Ⅰ
【解析】标准差相当于数组的偏差程度,偏差程度越大则标准差越大。正确答案为 E。
8. range 范围
最大数减去最小数所得的差就是该组数据的范围。
例 1:150, 200, 250, n
Which of the following could be the median of the 4 integers listed above?
Ⅰ. 175Ⅱ. 215Ⅲ. 235
Ⅰonly Ⅱonly Ⅰand Ⅱonly Ⅱand Ⅲ only Ⅰ,Ⅱ,and Ⅲ
【解析】由题可知,n 位于数字排序最右边时,取得最大的中位数=225,因此整个数字排序的中位数必
然小于等于 225,只有 I 和 II 符合要求。正确答案为 C。
例 2:The least and greatest numbers in a list of 7 real numbers are 2 and 20, respectively. The median of the
list is 6, and the number 3 occurs most often in the list. Which of the following could be the average of the
numbers in the list?
Ⅰ. 7Ⅱ. 8.5Ⅲ. 10.5
Ⅰonly ⅠandⅡonly Ⅰand Ⅲ only Ⅱand Ⅲ only Ⅰ,Ⅱ,and Ⅲ
【解析】7 个数,最小的是 2、最大的是 20、中间的是 6、3 出现次数最多,因此可以得出 7 个数从小到大排序
为:2、3、3、6、x、y、20。使用极端值假设法可以的出平均值介于 6.5 和 10.5 之间,因此 I、II 和 III 都符合
要求。正确答案为 E。
以上就是对统计这一GMAT数学知识点的全部介绍,分别从基本概念,解题方法等角度对这一概念进行的解释,最后祝大家都能考出好成绩。
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